opencv write webcam output to avi file
I am trying to create an avi video from my webcam output using opencv. No exceptions are thrown, however the avi file it creates is 414 bytes in size and does not grow.
Also it will not play with any media player. I suspect there is something wrong with the writing to file part.
Here is the code:
CvCapture *capture = cvCaptureFromCAM( 0 );
int width = ( int )cvGetCaptureProperty( capture,
CV_CAP_PROP_FRAME_WIDTH );
int height = ( int )cvGetCaptureProperty( capture,
CV_CAP_PROP_FRAME_HEIGHT );
CvVideoWriter *writer = cvCreateVideoWriter("CamCapture.avi",
-1,30, cvSize( width, height ) );
cvNamedWindow("capWindow", CV_WINDOW_AUTOSIZE);
IplImage *frame = 0;
// this returns 0 not sure why ??
//double fps = cvGetCaptureProperty(capture, CV_CAP_PROP_FPS);
double fps = 30;
while( 1 )
{
frame = cvQueryFrame( capture );
cvShowImage("capWindow",frame);
cvWriteFrame( writer, frame );
char c = cvWaitKey(1000/fps);
if( c == 27 ) break;
}
cvReleaseCapture( &capture );
cvReleaseVideoWriter( &writer );
cvDestroyWindow( "capWindow" );
I have referenced and tried the following samples with no luck:
不要使用过时的c，使用c ++ api，它很容易使用和简单，例如上面的代码可以在c ++中重写，
#include "opencv2/opencv.hpp"
#include <iostream>
using namespace std;
using namespace cv;
int main(){
VideoCapture vcap(0);
if(!vcap.isOpened()){
cout << "Error opening video stream or file" << endl;
return -1;
}
int frame_width= vcap.get(CV_CAP_PROP_FRAME_WIDTH);
int frame_height= vcap.get(CV_CAP_PROP_FRAME_HEIGHT);
VideoWriter video("out.avi",CV_FOURCC('M','J','P','G'),10, Size(frame_width,frame_height),true);
for(;;){
Mat frame;
vcap >> frame;
video.write(frame);
imshow( "Frame", frame );
char c = (char)waitKey(33);
if( c == 27 ) break;
}
return 0;
}
使用下面的代码从捕捉相机输入中编写AVI格式。
#include "opencv2/highgui/highgui.hpp"
#include <iostream>
using namespace cv;
using namespace std;
int main(int argc, char* argv[])
{
VideoCapture cap(0); // open the video camera no. 0
if (!cap.isOpened()) // if not success, exit program
{
cout << "ERROR: Cannot open the video file" << endl;
return -1;
}
namedWindow("MyVideo",CV_WINDOW_AUTOSIZE); //create a window called "MyVideo"
double dWidth = cap.get(CV_CAP_PROP_FRAME_WIDTH); //get the width of frames of the video
double dHeight = cap.get(CV_CAP_PROP_FRAME_HEIGHT); //get the height of frames of the video
cout << "Frame Size = " << dWidth << "x" << dHeight << endl;
Size frameSize(static_cast<int>(dWidth), static_cast<int>(dHeight));
VideoWriter oVideoWriter ("D:/MyVideo.avi", CV_FOURCC('P','I','M','1'), 20, frameSize, true); //initialize the VideoWriter object
if ( !oVideoWriter.isOpened() ) //if not initialize the VideoWriter successfully, exit the program
{
cout << "ERROR: Failed to write the video" << endl;
return -1;
}
while (1)
{
Mat frame;
bool bSuccess = cap.read(frame); // read a new frame from video
if (!bSuccess) //if not success, break loop
{
cout << "ERROR: Cannot read a frame from video file" << endl;
break;
}
oVideoWriter.write(frame); //writer the frame into the file
imshow("MyVideo", frame); //show the frame in "MyVideo" window
if (waitKey(10) == 27) //wait for 'esc' key press for 30ms. If 'esc' key is pressed, break loop
{
cout << "esc key is pressed by user" << endl;
break;
}
}
return 0;
}